Mechanical brake

ABSTRACT

A mechanical brake having an axial shifting mechanism arranged on an input drive shaft and an axial shifting mechanism arranged on an output drive shaft. The two axial shifting mechanisms are so embodied that their shifting directions are opposed and that, upon introduction of a torque via the input drive shaft and/or the output drive shaft, the axial shifting mechanism associated with the input drive shaft has precedence over the axial shifting mechanism associated with the output drive shaft.

This application is a nonprovisional application which claims thebenefit of U.S. Provisional Application No. 61/071,396 filed on Apr. 28,2008.

TECHNICAL FIELD

The invention relates to a mechanical brake.

BACKGROUND DISCUSSION

In the field of actuator drives, load torque blockers are regularly usedto enable an unhindered operation of a machine part in both directionsby means of a rotary drive, for example with the help of a motor or ahand-wheel, while blocking, in both directions, reverse-acting torquesof the driven part on the drive, without an additional braking systembeing needed therefor.

Electrical actuator drives for operating elements must be designed suchthat they can transmit, at low rotational speeds (4-180 RPM), hightorques (30-500,000 Nm), wherein the transmitted torques must be highlyconstant at small angles of rotation.

In the case of known actuator drives, torque transmission between anelectric motor and an operating element, such as a valve, isaccomplished via a speed-reduction transmission. The speed-reductiontransmission is necessary, in order to convert the high RPM of theelectric motor into the desired, highly constant, drive RPM foractuating the operating element. Preferably, worm-gear transmissions areused as the speed-reduction transmissions and are so embodied that theyexhibit a self-braking characteristic. The advantage, that an accidentaland undesired rotation of the drive shaft can be effectively blocked bythe intrinsic self-braking, is bought with the disadvantage that totalefficiency falls.

DE 10 2004 048 366 B1 discloses a direct drive, or direct actuator, inthe case of which the drive shaft is directly and immediately connectedwith the actuating member, or operating element. Thus, there is nointerposed, however fashioned, transmission for converting the motor RPMto the drive RPM for actuating the operating element. The exactpositioning of the actuator drive is accomplished via a suitableelectric control of the electric motor. The disclosed, direct drive isdistinguished, especially, by the fact that an additional brakingapparatus can be omitted for the electric motor. The blocking occurselectrically, in that the coils of the coil arrangement are shortcircuited by the control in the case of a separate actuating of thedrive shaft via the actuating wheel. If, now, the actuating wheel isactuated, there is induced in the stator of the electric motor a voltagewhich acts against the torque exerted by the actuating wheel.

Furthermore, the state of the art discloses special mechanical torque,or load torque, blockers. The torque, or load torque, blocker known fromDE 85099971 U works according to the jamming roller, or jamming wedge,principle. In this case, a closed, annular housing contains a fitting,cylindrical, inner element, which is connected, secured againstrotation, with the output drive part, thus the part to be driven. Thecylindrical, inner element has on its periphery a recess, in which arearranged jamming rollers, in each case biased in the outer direction byjamming springs. These block rotation of the cylindrical, inner elementrelative to the annular, outer housing. Arranged between the two jammingrollers is a ridge-shaped input drive part, which is e.g. part of thehand-wheel. If this input drive part is rotated in one or the otherdirection of rotation, one of the two jamming rollers is releasedagainst the force of the pressure spring and the output drive part canbe displaced. In this instance, the second jamming roller is free.Reverse torques from the output drive part are, in contrast, blocked inboth directions of rotation.

Rotary drives with torque blockers according to the jamming rollerprinciple are used, for example, for position securement on displacementdrives for machine parts. Furthermore, they serve e.g. for securementand hand displacement of gate drives, for hatch and window securement,or for rebound safety in the case of control, or shutoff, valves. Thedisadvantage of the known torque blocker operating according to thejamming roller, or also jamming wedge, principle is to be seen in thefact that these torque blockers can show a critical blocking behavior.Additionally, they experience a relatively high wear, since, by therepeated jamming and subsequent releasing of the jamming elements, thecomponents coming in contact with one another are exposed to highfrictional forces. Due to the loss of dimension or possible deformationof the material, a continuing worsening of the blocking function can beexperienced. In the case of a consideration from the point of view ofeconomics, it is evident that torque blockers operating on the basis ofthe jamming roller principle are unsuitable for application at higherRPMs.

WO 2006/0063874 A1 discloses a torque blocker for an actuator drive forlikewise preventing the transmission of reverse-acting torques from anoperating element onto the drive part. To this end, arranged in ablocking ring are a wrap spring and a two-part drive shaft, with anentrainment mechanism on the input drive side and a blocking mechanismon the output drive side. The entrainment element is mounted on theinput drive shaft of the torque blocker, while, on the output driveshaft of the torque blocker, a blocking piece is secured. The two endregions of the entrainment element lie against the inner sides of thespring ends of the wrap spring.

As soon as the torque blocking drive shaft rotates due to a torqueintroduction from the input drive side, the entrainment element driveswith, in each case, one of its end regions, the wrap spring via theinner sides of the spring ends. The wrap spring is, because of this,released from the blocking ring, whereby a rotation of the output driveshaft is possible. If a reverse-acting torque is introduced via theoutput drive shaft of the torque blocker, e.g. from the valve, then,depending on direction of rotation, the pertinent end region of theblocking piece is pressed from the outside on one of the spring ends,whereby the wrap spring is pressed under force against the blockingring, whereby a rotation of the output drive shaft is effectivelyprevented. Also with this known solution, high RPMs cannot beimplemented, so that torque blockers operating according to thewrap-spring principle can be very advantageously applied on thetransmission output side, but they are less applicable on thetransmission input side.

A torque limiter is available from the firm, Ringspann, under thedesignation, Durchratsch-Sikumat (Through-Ratcheting Sikumat). A brakecone secured to the output drive shaft is, for purpose ofbraking/locking, pressed via a pressure spring into a corresponding,fixed, housing part. Between the input drive shaft and the brake conelie, on both sides, inclined switching surfaces with, as required, ballslying therebetween. If a rotation is initiated via the input driveshaft, the balls roll on the inclined planes and press the brake coneout of its seat in the housing. By the interruption of the frictionalcontact between the brake cone and the housing, a torque is transmittedvia the input drive shaft to the output drive shaft. This known torquelimiter is embodied as a mechanical safety system, which, upon reachinga set limiting torque, separates the output drive from the input drive,and so protects against damage or down time. Following removal of theoverload, the torque limiter automatically re-engages. A limit switchsignals reaching of overload, so that suitable countermeasures can beundertaken.

A disadvantage of this known solution is that the braking action islimited by the spring force of the pressure spring. As soon as theoutput drive torque becomes greater than the braking torque, which isproduced by the spring force of the pressure spring, the torque limiterslips and a safe clamping function is no longer assured. This knownsolution is, therefore, not usable as a torque blocker.

SUMMARY OF THE INVENTION

An object of the invention is to provide a self-reinforcing andself-actuatingly controlling, mechanical brake, especially a mechanical,motor brake.

The object is achieved by the features that the mechanical brake,especially a motor brake, is equipped with an axial shifting mechanismarranged on an input drive shaft and an axial shifting mechanismarranged on an output drive shaft, wherein the two axial shiftingmechanisms are so embodied that their shifting directions are oppositeand that, in the case of introduction of a torque via the input driveshaft and/or the output drive shaft, the axial shifting mechanismassociated with the input drive shaft has precedence over the axialshifting mechanism associated with the output drive shaft. The brake,especially the motor brake, of the invention has the advantage that itself-actuatingly controls itself, when a torque is introduced from theoutput drive side. Furthermore, the brake of the invention works purelymechanically.

In a preferred embodiment of the brake of the invention, the axialshifting mechanism associated with the input drive shaft is an axialextraction mechanism, while the axial shifting mechanism associated withthe output drive shaft is an axial insertion mechanism.

The axial extraction mechanism and the axial insertion mechanism arepreferably so embodied that they work in the following manner: For thecase in which the magnitude of the torque introduced via the input driveshaft is greater than the magnitude of the torque introduced via theoutput drive shaft, the axial extraction mechanism is unlocked and theaxial insertion mechanism is locked, so that torque is transmitted fromthe input drive shaft to the output drive shaft. If, in contrast, themagnitude of the torque introduced via the input drive shaft is smallerthan the magnitude of the torque introduced via the output drive shaft,then the extraction mechanism and, consequently, the input drive shaft,is locked. The greater the torque introduced via the output drive shaftin comparison to the torque introduced via the input drive shaft, thestronger and more effective is the locking of the input drive shaft. Tobe mentioned is that, from the side of the input drive shaft, each ofthe two rotational directions is transmitted onto the output driveshaft.

If, in contrast, no torque is introduced via the input drive shaft andno torque is introduced via the output drive shaft, then the axialextraction mechanism is locked by the action of the predetermined springforce of a spring element. This spring element is so designed that, inevery case, a sufficient locking action is achieved.

If there is no torque applied to the input drive shaft, while a torqueis acting on the output drive shaft, then the locking action of theaxial extraction mechanism by the torque introduced via the output driveshaft is, as already mentioned above, still further strengthened.Consequently, it is always assured that no torque leading to a highlyundesired rotation of the input drive shaft is transmitted from theoutput drive shaft to the input drive shaft.

In an advantageous embodiment of the brake of the invention, a first,rotationally symmetric, braking element, which is rigidly connected withthe housing of the brake, especially motor brake, and a secondrotationally symmetric, braking element, which is connected with theoutput drive shaft, are provided. The two braking elements cooperate,due to their complementary forms, or constructions, such that, in thecase of locking of the extraction mechanism, the locking, or braking,effect occurs by a mechanical contact between the braking surfaces ofthe first braking element and the second braking element.

Furthermore, it is provided that the axial extraction mechanismassociated with the input drive shaft is arranged on a smaller radiusfrom the longitudinal axis of the input/output drive shaft than is theaxial insertion mechanism associated with the output drive shaft. Inthis way, it is assured that the axial shiftings do not mutually blockone another, when torques are introduced simultaneously via the inputdrive shaft and the output drive shaft.

Additionally, it is provided that the axial extraction- and/orinsertion-mechanism are/is composed of, in each case, two switchingrings having inclined switching surfaces, which, in the case of a torqueintroduction via the output drive shaft, are displaceable by an anglealpha relative to one another.

An alternative embodiment, instead of the above-described solution, inwhich the axial extraction mechanism associated with the input driveshaft is arranged on a smaller radius from the longitudinal axis of theinput/output drive shaft than the axial insertion mechanism associatedwith the output drive shaft, provides as follows: The axial extraction-and/or the axial insertion-mechanism have/has recesses with inclinedswitching surfaces, wherein the recesses on the switching rings of theinput drive side, extraction mechanism and the recesses on the switchingrings of the output drive side, insertion mechanism have a differentslope and/or a different dimensioning. This permits optimizing of boththe braking force, as well as also the responsive behavior of the brake,or motor brake.

For the purpose of attaining a better efficiency—instead of slidingfriction, there occurs, now, a rolling friction—a switching element isarranged between each two switching surfaces of the switching rings.Preferably, the switching elements are balls, rollers or needles. Inthis way, wear on interacting components can be minimized. In thisconnection, in a preferred embodiment of the apparatus of the invention,it is provided that the diameter of the balls arranged between the twoswitching rings of the extraction mechanism differs from the diameter ofthe balls arranged between the switching rings of the insertionmechanism. In this way, the danger already mentioned above of theblocking of the brake in the case of simultaneous torque introductionfrom the input drive side and the output drive side is avoided. Ingeneral, it can be said that the responsive behavior of the brake isimproved.

Furthermore, it is provided that the first rotationally symmetric, brakeelement is arranged not rigidly (as already described above), but,instead, torque-softly on the housing of the brake. This embodiment has,as compared to the rigid connection between the braking element and thehousing, the advantage that the brake does not respond immediately, orabruptly. To achieve a torque-soft arrangement of the braking element onthe housing, an elastomeric ply, a spring and/or a damping element canbe applied.

As already mentioned above, the brake described in various variantsabove is preferably usable as a motor brake. Especially advantageous isits application as a torque blocker in an actuator drive.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be explained in greater detail on the basis ofthe drawing, the figures of which show as follows:

FIG. 1 a longitudinal section through a preferred embodiment of themotor brake of the invention;

FIG. 2 a longitudinal section in different planes through a simplifiedrepresentation of the motor brake of the invention;

FIG. 2 a a cross section taken according to the cutting plane A-A ofFIG. 2;

FIG. 3 a first arrangement of the motor brake of the invention in anactuator drive; and

FIG. 4 the second arrangement of the motor brake in an actuator drive.

DETAILED DISCUSSION IN CONJUNCTION WITH THE DRAWINGS

The motor brake 1 of the invention is, as shown in FIG. 1, aself-actuatingly switching and self-reinforcing, mechanical, motor brake1, which is distinguished by the following functions: Torque introducedvia the input drive shaft 2 is transmitted in both directions ofrotation. In contrast, torque introduced via the output drive shaft 3reinforces the braking action of the motor brake 1 in both directions ofrotation, when a torque is not transmitted simultaneously via the inputdrive shaft 2 onto the output drive shaft 3. If torques aresimultaneously introduced via the input drive shaft 2 and the outputdrive shaft 3, then the torque introduced via the input drive shaft 2has precedence over a torque of equal or opposite sense introduced viathe output drive shaft 3, when the magnitude of the torque on the inputdrive shaft 2 is greater than the torque on the output drive shaft 3.

FIG. 1 shows a longitudinal section through a preferred embodiment ofthe brake 1 of the invention. As already explained, the brake workspreferably as a motor brake in connection with an actuator drive. Brake1 is arranged, for example, in an intermediate flange between the motor27 and the transmission 28.

The input drive shaft 2 is journalled via a bearing 23 in brake flange7. In the illustrated case, bearing 23 is a grooved, ball bearing. Ofcourse, also other bearings are best suited for this application, forexample a bearing with inclined indexing surfaces on both sides, with orwithout balls placed therebetween. Reference is made, in thisconnection, to the already mentioned Through-Ratcheting Sikumat.

The brake cone 6 is connected by shape-interference via a key 20 withthe input drive shaft 2. The output drive shaft 3 is seated on the inputdrive shaft 2. Output drive shaft 3 held against axial displacementrelative to the input drive shaft 2 by a screw 24 and a washer 25.Output drive shaft 3 is secured against undefined rotation relative tothe input drive shaft 2 by a key 20 in a manner so as to providetangential play, i.e. the groove 26 is somewhat wider than the key 20.The maximum angular displacement is so selected that a sufficientswitching path is available for releasing the brake 1.

Via the pressure spring 21, the motor brake 1 is preloaded, such that adefined braking torque is set on the output drive side. The spring forceof the pressure spring 21 is preferably so sized that it compensates theweight of the brake cone 6. Especially, it is provided that the motorbrake 1 can be released even during idling. In this way, it achievedthat the motor brake 1 safely brakes in the face of a load torque fromthe output drive side under all operating conditions.

Essential components of the motor brake 1 are the input drive side,axial extraction mechanism 4 interacting with the input drive shaft 2and the output drive side, axial insertion mechanism 5 interacting withthe output drive shaft 3. Both axially acting mechanisms 4, 5 move thebrake cone 6 in the axial direction relative to the brake flange 7. If atorque is introduced via the input drive shaft 2, the brake cone 6 ismoved axially out of the brake flange 7 against the spring force of thepressure spring 21, and the torque is transmitted onto the output driveshaft 3. A torque introduced via the output drive shaft 3 presses thebrake cone 6 additionally against the brake flange 7. Due to theincreased friction in the region of the braking surfaces between thebrake cone 6 and the brake flange 7, a rotation of the input drive shaft2, and thus a transmission of the torque from the output drive side, isreinforcingly prevented. An additional torque applied by the outputdrive side, axial insertion mechanism 5 increases, by a number of times,the intrinsic braking action (as a result of the preloading by thepressure spring 21) between brake cone 6 and braking flange 7 in thecase of absent torque on the input drive side. Consequently, the motorbrake, or torque blocker, of the invention works in a self-reinforcingmanner.

The simplified, sectional drawing of FIG. 2 displays fundamentalindividual components and manner of operation of the axial shiftingmechanisms 4, 5 of the motor brake 1 of the invention. Essentialcomponents of the motor brake 1 of the invention include the brakeflange 7, which is securely connected to a housing (not shown), and thebrake cone 6 interacting via frictional contact with the brake flange 7in the zone of the braking surfaces 22 a, 22 b. Arranged on the inputdrive shaft 2 is the input drive side, axial extraction mechanism 4. Theaxial insertion, or locking, mechanism 5 is arranged on the output driveshaft 3.

The following presentation considers the manner of operation of themotor brake 1 of the invention in detail for various different cases:

-   -   If the motor 27 is not operating, motor brake 1 is nevertheless        always activated by the insertion mechanism 5 and the pressure        spring 21. The motor brake has the action of a holding brake.    -   If a torque is introduced via the output drive shaft 3 and if        such is greater than the torque introduced via the input drive        shaft 2, then the motor brake 1 acts again as a holding brake        with reinforced braking action—such as has already been        explained above.    -   If motor 27 is turning and if the torque of the motor 27 is        magnitude-wise greater than the torque introduced via the output        drive shaft 3—this corresponding to the case: ‘no advancing        load’—, then the extraction mechanism 4 acts against the spring        force of the pressure spring 21 and this torque suffices to        release the motor brake 1 of the invention and to turn the        output drive shaft 3. The torque necessary to extract the        extraction mechanism 4 against the spring force of the pressure        spring 21 corresponds to an internally lost torque; the motor 27        must only be designed stronger than this relatively small, lost        torque.    -   If motor 27 is rotating and if the torque of the motor 27 is        magnitude-wise smaller than the torque introduced via the output        drive shaft 3—this corresponding to the case: ‘advancing load’—,        then the extraction mechanism 4 releases itself from the driving        ball-ring 8 with the at least one ball 13. After a short time,        the counterflank 16; 17 of the recess 18 presses again on the        ball 19. At this point in time, the motor brake 1 is again        active. As a result of the sequential releasing and engaging of        the motor brake 1, it is self-actuatingly controlled.

The extraction mechanism 4 on the input drive side includes thefollowing components: The two ball rings 8, 9, which have on theiropposing surfaces milled-in recesses 12 having inclined switchingsurfaces 10, 11. In the illustrated case, these recesses 12 are, forexample, embodied as ball-run grooves, in which balls 13 are guided. Atleast one ball-run groove 12 is provided on a circular ring. Shown inFIG. 2 is a preferred embodiment with three ball-run grooves 12. Thisprovides a high accuracy of response and a play-free torquetransmission. As already mentioned, instead of the ball-run rings, alsorings with helical surfaces, double rollers or single rollers can beutilized.

Located on the output drive side are likewise two ball rings 14, 15,having, on their opposed surfaces, milled-in recesses 18 with inclinedsurfaces 16, 17. Also here, the recesses 18 are embodied as ball-rungrooves, in which the balls 19 are guided.

Operation of the axial shifting mechanisms is shown simplified in FIG.2: Essential components of the motor brake 1 are the brake cone 7interacting with the brake flange 6, as well as the input drive side,extraction mechanism 4 and the output drive side, insertion mechanism 5.The release mechanism of the input drive side, extraction mechanism 4and the locking mechanism of the output drive side, insertion mechanism5 have on each two, oppositely-lying surfaces, recesses 12; 18, wherein,in each case, a ball 13; 19 is guided between a pair of recesses 12; 18.If a torque is introduced via the input drive shaft 2, the two shafts 2,3, and, thus, the two ball rings 8, 9 are rotated relative to oneanother over the balls 13. Since the balls 13 roll on the inclinedflanks 10, 11 of the recesses 12, a bounded, axial extraction of thebrake cone 6 from the brake flange 7 is achieved: The input drive shaft2 and the output drive shaft 3 rotate freely.

If a torque is introduced via the output drive shaft 3, then the balls19 roll likewise on the inclined flanks 16, 17 of the recesses 18 andpress the brake cone 6 into the brake flange 7. Since the motor brake 1then locks, a torque introduced via the output drive shaft 3 is nottransmitted to the input drive shaft 2 and thus also not to the motor27. In the case of a torque introduction via the output drive shaft 3,the axial extraction mechanism 4 and the axial insertion mechanism 5 aredisplaced relative to one another maximally by an angle alpha. This isillustrated in FIG. 2 a, which shows a cross section taken according tothe cutting plane A-A of FIG. 2.

According to the invention, it must be assured that the axial shiftingsdo not mutually block one another, when torques are introducedsimultaneously via the input drive shaft 2 and the output drive shaft 3.This is achieved by the fact that the switching elements 12, 13; 18, 19of the input drive side, extraction mechanism 4 and the output driveside, insertion mechanism 5 are arranged on different radii; theswitching elements 12, 13 of the input drive side, extraction mechanism4 are arranged on a smaller radius then the switching elements 18, 19 ofthe output drive side, insertion mechanism 5. In the case of arotational movement of equal- or opposite-sense by the operatingelement, e.g. valve, 31 on the output drive shaft 3 coupled withsimultaneous rotational movement on the input drive shaft 2, prioritytherefore always lies with the input drive side, i.e. when a rotationalmovement is applied to the input drive shaft 2, the brake cone 6 ispressed out of the brake flange 7 via the inclined planes 10, 11 of therecesses 12 and the balls 13, and the rotational movement is transmittedto the output drive shaft 3. If no rotation is applied to the inputdrive shaft 2, then as a result of the rotational movement at the outputdrive shaft 3, the axial output drive side, insertion mechanism 5 of theoutput drive shaft 3 will act via the balls 19 on the inclined planes16, 17 of the recesses 18 and, lastly, on the brake cone 6. Byintroduction of a torque from the output drive shaft, thus a lockingaction is achieved.

FIGS. 3 and 4 show, schematically, different forms of embodimentillustrating how the motor brake 1 of the invention can be utilized inan actuator drive 29. In the case of the form of embodiment shown inFIG. 3, the input drive unit, here a motor 27, operates the operatingelement 31 directly via the input drive shaft 2 and the output driveshaft 3. Operating element 31 is, preferably, an adjusting element, e.g.a valve or a gate (in each case with a spindle and a threaded member onthe spindle), a throttle or a damper. Depending on the adjusting element31, the actuation, or the displacement process, introduced via the driveunit 27 is a rotational movement or a swinging movement.

Drive unit 27 is preferably a direct drive. However, it is also possibleto provide after the electric motor 27 a first speed-reductiontransmission 32. Of course, alternatively or additively to theelectrical drive unit 27, also a separately actuatable, adjusting wheel30, e.g. a hand-wheel for manual actuating of the operating element 31,can be used. The torque blocker of the invention, or the motor brake 1of the invention, is associated with the input drive shaft 2.

FIG. 4 is a schematic illustration of a second embodiment of how thetorque blocker, or motor brake 1, of the invention can be advantageouslyapplied in the case of an actuator drive 29. The form of embodimentshown in FIG. 4 differs from that shown in FIG. 3 by a secondspeed-reduction transmission, which is arranged on the output driveshaft 3 between the first speed-reduction transmission 28 and theoperating element 31. Speed-reduction transmission 32 is, preferably, aworm-gear transmission. Worm-gear transmissions are usually so designedthat they possess an intrinsic self-blocking, which effectively preventsan unintended rotation of the output drive shaft 3. Such an actuatordrive 29 is especially advantageous, since, due to the torque blocker 1between the drive part 27 and the first speed-reduction transmission 28,the intrinsic self-blocking of the first speed-reduction transmission 28and a present, second speed-reduction transmission 32 does not have tobe relied on. In this way, the total efficiency of the actuator drive 29can be significantly improved.

1. A mechanical brake, comprising: an input drive shaft; an output driveshaft; an axial, shifting mechanism arranged on said input drive shaft;and an axial, shifting mechanism arranged on said output drive shaft,wherein: the two axial shifting mechanisms are so embodied, that theirshifting directions are opposite and that, in the case of introductionof a torque via said input drive shaft and/or said output drive shaft,said axial shifting mechanism associated with said input drive shaft hasprecedence over said axial shifting mechanism associated with saidoutput drive shaft, wherein: said axial shifting mechanism arranged onsaid input drive shaft is arranged on a smaller radius relative to thelongitudinal axis of said input/out drive shafts than said axial,shifting mechanism arranged on said output drive shaft.
 2. Themechanical brake as claimed in claim 1, wherein: said axial shiftingmechanism associated with said input drive shaft is an axial extractionmechanism; and said axial shifting mechanism associated with said outputdrive shaft is an axial insertion mechanism.
 3. The mechanical brake asclaimed in claim 2, wherein: said axial extraction mechanism and saidaxial insertion mechanism are so embodied that they work as follows: forthe case in which the magnitude of the torque introduced via said inputdrive shaft is larger than the magnitude of the torque introduced viasaid output drive shaft, said axial extraction mechanism is unlocked andsaid axial insertion mechanism is blocked, so that torque is transmittedfrom said input drive shaft to said output drive shaft.
 4. Themechanical brake as claimed in claim 2, wherein: said axial extractionmechanism and said axial insertion mechanism are so embodied that theywork as follows: for the case in which the magnitude of torqueintroduced via said input drive shaft is smaller than the magnitude oftorque introduced via said output drive shaft, said extraction mechanismand, thus, said input drive shaft are locked.
 5. The mechanical brake asclaimed in claim 2, further comprising: a spring element, wherein: saidaxial extraction mechanism and said axial insertion mechanism are soembodied that they work as follows: for the case in which no torque isintroduced via said input drive shaft and no torque is introduced viasaid output drive shaft, said axial extraction mechanism is locked viaaction of a predetermined spring force of said spring element.
 6. Themechanical brake as claimed in claim 2, wherein: in the case that notorque lies on said input drive shaft and torque lies on said outputdrive shaft, the blocking action of said axial extraction mechanism isreinforced by the torque introduced via said output drive shaft.
 7. Themechanical brake as claimed in claim 1, further comprising: a first,rotationally symmetric, brake element, which is rigidly connected withsaid housing of the brake; and a second, rotationally symmetric, brakeelement, which is connected with said output drive shaft, wherein: saidtwo brake elements so interact due to their complementary shapes, that,in the case of locking of said extraction mechanism, blocking- orbraking-action of said first brake element and said second brake elementis effected.
 8. The mechanical brake as claimed in claim 7, wherein:said rotationally symmetric brake element is not rigid, but, instead, isarranged torque-softly on said housing of the brake.
 9. The mechanicalbrake as claimed in claim 2, wherein: said axial extraction mechanismassociated with said input drive shaft is arranged on a smaller radiusrelative to the longitudinal axis of said input/output drive shafts thansaid axial insertion mechanism associated with said output drive shaft.10. The mechanical brake as claimed in claim 2, wherein: said axialextraction- and/or insertion-mechanism are/is, in each case, composed oftwo switching rings having inclined switching surfaces, which, in thecase of a torque introduction via said output drive shaft, aredisplaceable relative to one another by an angle (alpha).
 11. Themechanical brake as claimed in claim 10, wherein: said axial extraction-and/or insertion-mechanism have/has recesses with inclined switchingsurfaces, said recesses on said switching rings of said input driveside, extraction mechanism and said recesses on said switching rings ofsaid output drive side, insertion mechanism have a different slopeand/or a different dimensioning.
 12. The mechanical brake as claimed inclaim 10, wherein: in each case, between two switching surfaces of saidswitching rings, a switching element is arranged.
 13. The mechanicalbrake as claimed in claim 12, wherein: said switching elements areballs, rollers or needles.
 14. The mechanical brake as claimed in claim13, wherein: said balls between said two switching rings of saidextraction mechanism have a diameter which is different from thediameter of said balls arranged between said switching rings of saidinsertion mechanism.
 15. The use of a mechanical brake described inclaim 1, for application as a torque blocker in an actuator drive.